Field of the Invention
The present invention relates to medical implant insertion delivery systems and, more particularly, to a delivery device for vascular prostheses.
Description of the Related Art
Medical implants, in particular stent-based implants, can be deployed in the vasculature of patients to treat a variety of ailments and medical conditions. The fragility of the vascular system tissue and the particular locations where a vascular prosthesis is required necessitates care and precision in the deployment of such implants. In particular, heart related implants, often comprising a valve body supported by a stent frame, present challenges in locating, positioning, and more specifically repositioning of the stent after partial or full deployment of the stent-based implant at a desired location.
A variety of methods and delivery devices aimed at delivering replacement heart valves through percutaneous and minimally invasive approaches currently exist. A primary challenge of known devices, such as those disclosed in U.S. Pat. No. 5,411,552 and U.S. Pat. No. 6,830,584, is the inability to reposition the replacement valve after it is fully deployed. For example, once a stent, or heart valve frame in particular, has been expanded via a balloon catheter, there is no way to reduce the diameter of the heart valve frame again. In another example, to deploy an implant comprising a self-expanding nitinol stent and heart valve body, a delivery device utilizes an outer sheath that is retracted to allow the implant to expand freely to a pre-determined diameter. However, again, once the frame is fully expanded, it cannot be collapsed to adjust, reposition, or remove the implant.
An additional short-coming with the noted delivery systems is that they are designed solely for use with their respective specific valve implant. A further short-coming of such approaches is their reliance on radial force as the primary means of fixation and the inability to accurately position the implant during initial deployment. The aforementioned devices consist of cylindrical frames, lacking features that can locate the implant relative to a native annulus of a heart valve. As a result, these devices must rely on external imaging during the delivery process, which can lead to improper placement of the implant and resulting complications and risks to the patient.